MerCruiser 3.0 Carb vs. MPI

[sohcfour]

First time posting, so bear with me...

My family is upgrading boats for the first time in 39 years. The 1971 Glastron AQ130 is taking its leave (runs well, any buyers?), and it looks like a new Sea Ray 175 is on the way in.

What I learned is that as of Jan. 2010, the 3.0L carb is no longer produced, replaced by an MPI and cat-equipped version. With the "special" boat show pricing, we can get either model for nearly the same price. I certainly understand the technological aspect of both motors. The carbed 3.0 is the trusty workhorse of the industry. MPI is ultra convenient, efficient, and the automotive standard for the past 20+ years.

What we're having trouble with is deciding on the best long-term solution. Clearly, we keep and maintain things for a long time. Fuel econ (and frankly emissions) are not an issue for us. Performance really isn't either (not like we're buying a V8). What matters is ease of use and dependability, as well as longevity.

So, forum, for the same price, do you say "tried and true carb" or lean toward a good deal on the "wave of the future?"

Thanks in advance!

Matt
Delavan, WI

 

[Don S]

Re: MerCruiser 3.0 Carb vs. MPI

I would stick to the carbed version. In 2009 Merc and Volvo had the 3.0 with MPI, in 2010 Volvo killed it, after only 1 year. I think I would let it get the bugs worked out before wanting to have one in my boat.
Let someone else deal with the problems.

 

[JustJason]

Re: MerCruiser 3.0 Carb vs. MPI

Aside from what Don said. I would look for a boat 1 or 2 years old, or perhaps a new leftover that does not run Cat converters. Cat's are very new in the marine world, nobody can really say for certain how long they are expected to last in fresh or salt water, and as of now, they would be very, very expenisive to replace should it fail. The same goes for the tbi system.
The TKS carbs work fine as long as you don't buy into the TKS crap and start the boat as you would any boat with a carb.

 

[sohcfour]

Re: MerCruiser 3.0 Carb vs. MPI

Two replies overnight, thanks! I thought I'd follow up and hopefully generate a few more responses. The pricing we're looking at is close enough to a gently used boat that it's worth going new. I also feel like the fuel injection system is known technology, but the catalyst is the question.

I'd heard about the Volvo 3.0 MPI, but there seems to be little info on either engine on the web. Does anyone have any good resources on either the Volvo or Merc 3.0 MPI??

Thanks for the advice so far, and hoping for a little more!

- Matt

 

[Don S]

Re: MerCruiser 3.0 Carb vs. MPI

I also feel like the fuel injection system is known technology,

Not on a 3.0L 2009 was the first year for the EFI 3.0L

 

[mylesm260]

Re: MerCruiser 3.0 Carb vs. MPI

There's two ways to look at this:

the EFI version is going to get better mileage, more torque and more HP and any given RPM, start better, be more predictable and in theory require less maintenance in the long run.


Having said all that, Don's right. Were not talking about a motor designed from the ground up. Where talking about an old non cross-flow design that they added EFI to in order to comply with 2010 EPA emission regulations.


Myself personally If I was hell-bent on the 3.0L I'd get the EFI, but you do whatever you're more comfortable with.

You know... an EFI'ed 4.3 is a SOLID motor.... you may want to reconsider upgrading.

 

[sohcfour]

Re: MerCruiser 3.0 Carb vs. MPI

It isn't so much a matter of being in love with the 3.0L engine, it's a size issue. We're limited to a boat that fits our existing lift in summer and garage in winter (so as not to add unnecessary cost). Those boats are almost exclusively powered by the 3.0.

I'm surprised how little info seems to exist on the internet. The 3.0 in any guise is the most common engine out there, and yet few test and zero comparison results exist!

 

[sohcfour]

Re: MerCruiser 3.0 Carb vs. MPI

I added a poll. I wish I'd thought of it earlier. I guess I'm leaning toward the carbed motor because it is a known entity. The devil you know versus the devil you don't, right?

Here's where I struggle. By all rights, MPI is a better technology. You couldn't pay me to slap a carb on my primary automobile anymore. So why claim a carb is superior in a boat? I've been an EFI calibrator in product development at Honda and Harley and I believe in the systems. What concerns me, and I guess everyone here, is how well developed the new engine is. Correct?

Two things stand out in this comparison:
1. Today, and in the near future, the carbed 3.0L is well known and supported. There will, however, come a day when it is the minority and a relic. Case in point, when our mechanic for the Glastron/Volvo B20 was killed snowmobiling, we wondered who would ever dial in the twin SU carbs on that thing.
2. MPI with On-Board Diagnostics will tell you what is wrong with it. Unfortunately, it will require a dealer with a scan-tool. That won't be cheap, but it is easy. No replacing multiple parts before you get it right.

 

[Don S]

Re: MerCruiser 3.0 Carb vs. MPI

2. MPI with On-Board Diagnostics will tell you what is wrong with it. Unfortunately, it will require a dealer with a scan-tool. That won't be cheap, but it is easy. No replacing multiple parts before you get it right.

ROFLMAO

 

[mylesm260]

Re: MerCruiser 3.0 Carb vs. MPI

ROFLMAO

Hey Don, you know I have a lot of respect for you're opinion, but honestly, I've gota call you out on this one.


In my opinion, OBD / OBD2 has been one of the biggest advances in automotive diagnostics technology.

Someone can go to their local auto parts store, and buy a 40 dollar scan tool that works with 95% of vehicles on the road and quickly diagnose a problem with the EFI system. Granted, they fault codes don't ALWAYS point in the right direction, but 99% of the times, they do.


I have used my scan tool to successfully diagnose several problems over the years. The vast majority of them have been O2 sensors or catalytic converters.


As I'm sure you know, I run automotive EFI in my boat. I can connect my automotive scan tool to my EFI harness (kept the automotive connector) and pull all kinds of data from my ECU.

Because I have no o2 sensors in my boat, I always get the o2 sensor fault codes, but my engine still runs perfectly (just no closed loop obviously)


Now, granted the marine diagnostics system won't use industry standard scan tools, but if he DOES have an issue, he can take it to any shop with the tool, and diagnose the problem very very easily.


What's so funny about that?




I mean... if you're carbed boat is running like crap, and you're not a "carb tuner" how do you know if you're float's failed, you're jets are clogged, you're linkage is bent or gummed up, etc etc.....

Carbs can fail in so many ways that to most people are NOT obvious. Even trained mechanics can screw up diagnosing carb issues (And do all the time)

YOU may feel more comfortable with a carb, but you have years of carb experience that most people don't.

 

[Don S]

Re: MerCruiser 3.0 Carb vs. MPI

In my opinion, OBD / OBD2 has been one of the biggest advances in automotive diagnostics technology.

The marine side does not use OBD or OBD2.

Someone can go to their local auto parts store, and buy a 40 dollar scan tool that works with 95% of vehicles on the road and quickly diagnose a problem with the EFI system. Granted, they fault codes don't ALWAYS point in the right direction, but 99% of the times, they do.

There are no $40 scan tools in the marine industry. A cheap on will cost you a minimum of $400 new.
Marine fault codes seldom tell the story of what the problem really is, and in my experience, 90% of the problems with EFI engines is marine related (Water, corrosion, etc) things you DO NOT see on the automotive end.

The vast majority of them have been O2 sensors or catalytic converters.

In the marine industry, O2 sensors and catalitic engines came out in 2009 and then only in California.

As I'm sure you know, I run automotive EFI in my boat.

Cool, but the OEM's like Mercruiser, Volvo, PCM, Crusader, Marine Power etc. don't.
They use marine rated and have to follow coast guard rules and regs. Along with they don't get to monitor each and every engine they manufacture.

Carbs can fail in so many ways that to most people are NOT obvious. Even trained mechanics can screw up diagnosing carb issues (And do all the time)

IF techs screw up carb diagnostics, think what they run into with EFI. There are very few trained techs out there that have a clue on how to diagnose #EFI properly. Mostly because it's still a fairly new on the Marine side.

The techs are still throwing all kinds of expensive EFI electrical parts at it hoping to find the problem, then they, or someone else, finds out their problem is water in the fuel and the EFI system, or the compression is down due to water in a cylinder or something else marine related and not found on the automotive side.

YOU may feel more comfortable with a carb, but you have years of carb experience that most people don't.

I wasn't posting about MY experience, I can do either. What I am talking about is the overall picture of marine techs all over the world. Less training ect. Don't forget, being a marine tech can be a part time job in most northern states and areas. Less training, less pay, etc. as compared to automotive.

I will stick with my ROML answer. Because in reallity, the marine industry is FAR from being taken over by EFI engines like the automotive side has.

Also remember one thing, this is the part that I was commenting on.

2. MPI with On-Board Diagnostics will tell you what is wrong with it. Unfortunately, it will require a dealer with a scan-tool. That won't be cheap, but it is easy. No replacing multiple parts before you get it right.

In the marine industry, there is a lot dealer experience and training in EFI, and a lot more parts replacing with EFI engines.
Sorry, but it a fact of life.
And a Very high percentage of boats out there are still equipped with carbs.

 

[ENSIGN]

Re: MerCruiser 3.0 Carb vs. MPI

I guess I'm from the old school like Don.There are times when the efi does make me feel uneasy.Can't give a opion about the converters except I'm not looking forward to working on them.The bottom line is the EPA is going to do what ever they want.

 

[mylesm260]

Re: MerCruiser 3.0 Carb vs. MPI

To me, this debate is more about the cat's then the EFI.

Here's a question:

Let's say you buy a boat with cats on it.
If those cats fail, could you not "downgrade" to the older risers/manifolds at that time to ones without cats?

I mean.... it's not like boats have smog testing, do they ? (I'm canadian and up here they don't)

you MAY loose you're o2 sensor as well during the downgrade, but it won't effect the performance of the engine, just the emissions and economy.

 

[ENSIGN]

Re: MerCruiser 3.0 Carb vs. MPI

You're going to see the emission testing sooner than you think!At one time we used to take the converters off our cars.Those days are long gone

 

[JustJason]

Re: MerCruiser 3.0 Carb vs. MPI

Look at it this way. Very seldom does a manufactor of anything get it right on the first try with a new technology.
MPI on a 3.o is a new technology.
Give it a few years to see if the manufactor is going to commit to the technology before you commit to it by purchasing the product.
If you own XYZ product and a manufactorer decides to drop or switch a certain technology, your going to get screwed in the long run.
This pertains to everthing from boats to toasters. With anything new, the first 2 to 3 years of something new is often the "debugging phase"

How many 3.0 owners are there here that have or had digital ignition systems that used $600 ignition coils that aren't supported anymore by Merc? What's worse, the cost of the coil when it failed or the cost of the conversion when you find out you can't get the coils anymore?

And as for scan tools.... hehehe. A code is a code, but ya need to know how to read a service manual, use a DMM, and close your eyes and THINK about how the EFI system works as a whole and how it intergrates with the mechanical system to effectively diagnose anything. Knowing how to read live data and what all the little numbers read, and what they should read, is much better than a code.

 

[jkust]

Re: MerCruiser 3.0 Carb vs. MPI

Call me crazy but EFI is my choice however I will take a 4.3 carb every day. Also lots of small boats offer the 4.3 as an option where a 3.0 is standard power. Generally an 18 footer and with a swing tounge trailer, garage size shouldn't stand in your way.

Volvo Penta 3.0L Shootout
Jim Barron
Trailer Boats
January 22, 2010
General Motors? 3.0L I-4 block has been around for decades. This classic four-banger was originally designed for vehicles such as the Chevy Nova, and there also was a higher-displacement six-cylinder version. Yet, it was the economically priced I-4 that caught hold as a sterndrive powerplant.

Today, the 3.0L is showing its age. The push-rod valve train limits rpm versus the newer overhead cam designs. Yet some things are timeless, and the 3.0L?s cast-iron construction, high torque and proven reliability are assets in marine applications.


Until recently, the marine 3.0L existed strictly as a carbureted powerplant. Now, we are seeing the same engine with electronic fuel injection (EFI) from both MerCruiser and Volvo Penta.

It?s important to remember that EFI is not a horsepower-enhancing system. It is simply a more efficient way to deliver fuel to the combustion chamber. A carburetor, when not encumbered with emission controls, works quite well. Any increase in power experienced with EFI is often due to other refinements, such as a modified cam, head, intake or exhaust.

HORSEPOWER MODS
In the case of Volvo Penta?its 3.0GXi with EFI?there have been extensive modifications to both the intake and exhaust manifolds that boost the horsepower to 150 versus 135 for the carbureted 3.0GL version.

The Volvo Penta EFI intake manifold is a long-runner design that wraps over the top of the engine. This enhances midrange torque by providing a tuned ram effect to force more of the fuel/air mix into the combustion chamber. The exhaust manifold also has been redesigned with an expansion chamber shape to help draw exhaust gasses out.

A comparison can be drawn with the 3.0L EFI from MerCruiser?it has a conventional manifold system and is rated at 135 hp, same as the carbureted version. Thus Volvo?s extra 15 hp does not come simply from the addition of EFI but rather from refinements to the manifold system.

There?s been a need for an engine in the 150- to 165-hp range for quite some time. The gap between the 135-hp 3.0L and the 190-hp 4.3L V-6 is substantial, and a lot of smaller boats could benefit from a bit more horsepower.

To see what the extra ponies would do, we decided to test both versions of Volvo?s 3.0L I-4 in a Stingray 195LX bowrider on South Carolina?s Lake Robinson, which is near the Stingray factory. At 191?2 feet and 2400 pounds, the 195LX was a
challenging test boat for a 3.0L sterndrive.

TESTING PROTOCOL
The first thing we did was run tests of the 195LX with the 135-hp carbureted 3.0GL. The tests included top speed, acceleration and fuel consumption. We also recorded acceleration when towing a ski drone, a device that mimics the affect of a skier on the boat?s acceleration.

We then replaced the engine with the 150-hp 3.0GXi EFI, using the same hull, SX drive and 21-inch-pitch Volvo Penta aluminum three-blade propeller, and then repeated the
tests. The prop held the engines in their rpm range but, as expected, the 150-hp engine turned the prop at a higher rpm. Let?s check out the test results.

Top speed with two adult males on board was 42.3 mph at 4650 rpm with the 135-hp engine. The 150-hp engine pushed the top speed to 44.2 mph at 4800 rpm, besting the carbureted version by nearly 2 mph.

Acceleration from 0 to 30 mph measured 8.2 seconds for the 135, and 6.9 seconds for the 150?no surprises there. What did surprise us was the difference when we ran acceleration tests with the ski drone attached.

Our 0-to-30-mph times climbed to 13.3 seconds for the 135, a 5.1-second difference from the unladen boat. The 150 required 10.8 seconds to reach 30 mph, a difference of 3.9 seconds. The 150-hp engine was clearly quicker at poping up skiers, and the difference will be most noticeable when trying to start a heavy skier on a single ski in deep water, often a struggle with the 135-hp engine.

SURPRISING FUEL EFFICIENCY
The fuel consumption data surprised us. We?d expect an EFI-equipped engine to do slightly better than a carbureted engine if both engines are of equal horsepower. EFI offers a more efficient method of delivering fuel, and maintains a more uniform fuel/air mix across the rpm range. With 15 additional horsepower, we also would expect the 150-hp 3.0L to burn more fuel across the rpm range. However, it doesn?t and it?s surprisingly more fuel efficient over much of the rpm range, particularly from slow displacement speeds (2000 rpm) through higher cruising speeds (4000 rpm). Only at idle speeds and near wide-open throttle does the 150-hp EFI burn more fuel than the 135-hp carbureted model.

The difference in fuel consumption will probably not make much of a difference when considering the overall costs of owning and operating a boat. Yet, there appears to be no penalty in choosing the more powerful engine. The cost difference is going to be most noticeable in the initial purchase price. The 135-hp Volvo Penta 3.0GL/SX sterndrive has a suggested retail of $9100. The 150-hp Volvo Penta 3.0GXi/SX stendrive with EFI is $10,880. The carbureted 190-hp Volvo Penta 4.3L V-6 is $11,135.

From a purely subjective view, the 3.0L with EFI was noticeably smoother than the carbureted unit. The carbureted engine had a slight tendency to hesitate when the throttle was popped open to accelerate, while the EFI engine was smooth and progressive throughout the rpm range. From the seat of your pants, the difference in acceleration and top speed was noticeable.

The 150-hp Volvo Penta 3.0GXi with EFI is a worthy upgrade for most entry-level boats?increasing performance without adding the mass of a larger 4.3L V-6. The 3.0L EFI was smoother and pulled better than its carbureted counterpart, while costing nothing extra in terms of increased fuel consumption.

Volvo Penta has certainly given this four-banger a boost.

 

[Don S]

Re: MerCruiser 3.0 Carb vs. MPI

The 150-hp Volvo Penta 3.0GXi with EFI is a worthy upgrade for most entry-level boats?increasing performance without adding the mass of a larger 4.3L V-6. The 3.0L EFI was smoother and pulled better than its carbureted counterpart, while costing nothing extra in terms of increased fuel consumption.

Volvo Penta has certainly given this four-banger a boost.

That report is fine, but the fact is, the 3.0GXi and GXiC (fuel injected engines) were all dropped, by Volvo, as of January 1, 2010. They were only available for ONE year. 2009.
The 3.0LGL (carbed engine) only has limited availablity in the US.

 

[jkust]

Re: MerCruiser 3.0 Carb vs. MPI

That report is fine, but the fact is, the 3.0GXi and GXiC (fuel injected engines) were all dropped, by Volvo, as of January 1, 2010. They were only available for ONE year. 2009.
The 3.0LGL (carbed engine) only has limited availablity in the US.

I wonder why they dropped the EFI and why the two day old article fails to mention that?? It would have had to be a dismal failure. Interesting the Stingray website indeed does not offer the EFI as an option any longer. I bet they researched the article having no idea it would be dropped by the time it made its way to the magazine but simply published it as is. Cliche as it is, I am really honestly amazed carbs didn't die a decade ago.

So my follow up question is that the article says that the EFI has nothing to do with the 15 hp increase, But I thought that on the 4.3 MPI, the MPI has everything to do with the 30 hp increase over carb??

 

[rodbolt]

Re: MerCruiser 3.0 Carb vs. MPI

from the tech bulliten Volvo sent us just before christmas of 2009 it said both the GL and the GXI were being dropped and no more 3.0L motors would be produced but dealers could still sell the remaining stock.
it also went on to say that only one version of the 5.7 and the 5.0L would remain. both injected with catalytic converters.
from what I have read the 4.3 is grandfathered from cats until 2011 and the 8.1 until 2012.
dunno what merc is gonna do nor the rest of the marinizers but the EPA regulations that hit the left coast last year get the rest of us in 2010.

 

[Don S]

Re: MerCruiser 3.0 Carb vs. MPI

I wonder why they dropped the EFI and why the two day old article fails to mention that??

Why, I don't have a clue. Maybe no one told them that the fuel injected 3.0L engines were discontinued, probably because they didn't ask.

If the article was in the magazine, testing, writing, editing and actual publication of the article were probably done several weeks or months ago to get it ready so the magazine could be published and delivered to customers on time.